Safety switch



Jam 29, 1929.

3 Sheets-Sheet 1 G. E. PALMER SAFETY SWITCH Filed May ll, 1925 G. E. PALMER SAFETY SWI TCH Jan. 29, 1929. v1,700,330

Jan. 29, 1929.

1,700,330 G. E. PALMER SAFETY SWITCH Filed May 11. 192s s sheets-snee@ S Patented Jan.. 29,1929.

UNITED STATES` PATENT OFFICE.

GRANVILLE E. PALMER, OF BROOKLINE, MASSACHUSETTS, ASISIGNQR, BY MESNE AS- SIGNMENTS, T THE PALMER ELECTRIC & MANUFACTURING CO., OFgWAT-TWAM. MASSACHUSETTS, A YCORPORATION' OF MASSACHUSETTS.

SAFETY SWITCH.

. Application led May 1.1,l 1925. Serial No. 29,286.

T his invention relates to electrical switches, particularly to that type of switch which is combined with a circuit closin fuse7 and which is commonly known as a safety-switch.

Switches of this kind are -most frequently employed as 'service switches for controlling the admission of current from a' power line y to the premises of a purchaser, and are in-` v cover and which may only be opened when the switch has been manipulated to break the circuit. Y

Objects of the present invention are to provide an improved switch ofthe above type 25 of simple and inexpensive character and having few essential parts; of compact constructionsuch that it may be installed in the space usually available for this purpose; effective to prevent theft of current at all times even Y when the fuse is exposed to view; affording' the requisite degree of safety tothe user; and easy'to operate and of pleasing external appearance. e, i

In the accompanying drawings a preferred 35 embodiment ofthe improved switch is illustrated byway of example;

Fig. 1 is a front elevation of the improved' switch with the parts in the position which .they occupy when the current is turned on;

Fig. Q isla side elevation of the switch with the parts in a similar position; i

Fig. 3 is a fragmentary front elevation of the switch with the parts in the position which \they occupy when the circuit is broken and with the fuse aperture opento permitrrenewal of the fuse plug.

Fig. 4 is a front elevation showing the switch box open to expose the circuit-closing elements; l y

Fig. 5 is a transverse section to larger yscale substantially on the line 5-5 of Fig. 1, some of the parts being omitted;

Fig. 6 is a side elevation ofthe base plate upon which the fuse-supporting means and4 the movable switch elements are mounted;

Fig. 7 is a, rear elevation of the device shown in Fig. 6; and

Fig. 8 is a diagram illustrating the wiring connections leading to and from the improved switch.

The improved switch comprises a boxlike container l, preferably of metal-or other strong and durable material, and`comprising the side walls 2 and 3, the rear wall 4, and the top and bottom walls 5 and "6. The container may conveniently be made of pressed sheet metal, although the exact construction of the container forms no essential feature of the present invent-ion.

This container is provided with a front wall or cover 7, preferably hingedat 8, and

having an aperture in its free edge through which may project a lug 7a secured to the side wall 2 of the container, such lug having4 an opening through which the wire 7b of a sealing device 7 may be passed. Any other suitable means for normally locking or sealing the cover in' closed position may be employed.

A base plate 8 (Figs. 5, 6 and 7), preferably of insulating material, is secured by suitable fastening means, as for example the rivets 9, to the inner surface of the rear wall 4of the container. The central part of the rear side of this base plate is preferably cut away ,so that the platebears against the wall 4 only along its marginal portions 10. The central part'llof the base plate is thus spaced from the inner surface of the wall 4 of the container for a purpose hereinafterdescribed. The base plate 8 is furnished withl a centrally disposed aperture whose axis issubstantially perpendicular to the wall 4 of the container, and a bracket member of substan-l tially U-shape is j'ournalled to turn in this opening. This bracket is preferably formed of sheet material and comprises the spaced parallel legs 12 and 18 connectedy at one end by the member 14 and having oppositelyl directed ears 15 and 16 respectively at their free ends.

A metallic washer 17 is preferably set into the surface 11 of the plate 8,'such washer being concentric with the journal vopening in the plate. A lever arm 18, which is disposed in the space between the wall 4 and the under surface 11 of the plate 8, projects A support 23, preferably of insulating material and preferably though not .necessarily of generally frusto-conical form, is mounted upon the ears 15 and 16. Any suitable means may be employed for attaching the larger end of this supporteto the ears.

The smaller end of the support 23 is furnished with an axial bore or socket 24 for the ureception of a fuse recep-tacle having rel-vr atively insulated contact elements, of which the metallic shell 25 constitutes one, and the screw head 26 constitutes the other. The screw of which vthe head 26 forms a part has threaded engagement with an axial. opening in the support 23 and thus retains the receptacle in proper position.y This receptacle is adapted to receive a fuse plug 29 of any usual type having the terminal members 27 and 28 which make electrical contact withthe members 25 and 26 respectively of the receptacle.

A metallic switch element 30, preferably of blade-like form, is secured to the support 23, preferably by clamping Ait between the base of the support and one orV both of the ears 15 or 16. This switch blade is connected electrically to the contact element26 of the receptacle, preferably by permitting the screw, of which the contact element 26 forms the head, to have threaded engagement with the blade 30. I A second switch element 31, also preferably in the form of'a blade, andA preferably extendingl in a direction diamtrically opposite to the blade 30 passesthrougha suitable opening in the side wall 23 and makes electrical contact withthe member 25ct the receptacle. This blade 31 is insulated ,from

elements 34 and 34h (Fig. 6) between whichv the blades 30 and 31 enter to make proper contact between the parts. Suitable .con-

ductors 36 and 37 are connected to the switchelements 34 and 35, the arrangementA described being suchthat when the switch elements are engaged and the fuse 29 is.proper' ily seated a continuous electrical connectionis provided between the conductors 36 and 37. The cover 7 of the box preferably com* prises a piece of sheet metal turned in at its edges to provide flanges overlap-ping the sides of the box proper and `having at its central part an annular guard member 43, preferably of frusto-conical shape, which projects inwardly from thev plane of themain body of the cover. This guard member 43 may be integral with the body of `the cover and formed by a stamping .or punching operation or `constructed as hereshown from a separate piece of metal having an attaching flange 44 lsecured to the body of the cover in any appropriate manner, for example by brazing or spot-welding. This guard 44 de- -fines a funnel-like opening 38 leading inwardly form an aperture 38a in the body of the cover, such funnel-like opening constituting a chamber for housing the fuse block.

The underside of the coveris provided with suitable guide flanges 39 for guiding a sliding ,closure plate 40 which normally closes v the entrance to the opening 38. j

The funnel-like opening 38 is coaxial with the journal opening in the base plate 8 and when the cover 7 is infclosed position the inner or smaller end of the opening 38- is closed by the outer-end ofthe support 23. The outer end of the support 23 is/preferably of reduced diameter as indicated at 41, thus providing y an annular shoulder 42 and the reduced por-Y tion of the support preferably projects into the funnel-like opening 38.

The smaller end of the guard 43 is turned into provide an annular flange 45 which sur! rounds the forward end portion 41 of the support 23 and cooperates with the shoulder 42 to prevent insertion of a conducting element through the. aperture 38a and into contact with any of the switch elements.

straight central port-.ion 46 is journalled to turn in an opening in the side wall 2 of the box. Preferably a bracket 46?l is provided at the inner side of the wall 2 having a supplementary journal opening for the member 46 whereby to steady the latter, This handle also comprises an arm 47 disposed within the box and having a member 48 which engages an elongate opening 49 (Fig. 6) inthe ienv A handle comprising a substantially#I outwardly projecting end 50 of the lever 18. j

The handle also comprises a hand grip arm 5l constituting the actuating member disposed outside of the box and which is guided in its swinging movement by means of a bracket 52 having a slot 53 in which the member 51 oscillates The closure plate 40 is furnished with a part 54 which projects ,out through the side wall 2 of the box and in some positions of the handle member 51 the latter lies in the path of the member 54 and thus prevents the closure plate 40 from being withdrawn to'uncover the aperture 38.

an aperture having an upstanding flange 55 to which the usual meter 56, indicated in broken lines, is secured. This meter comprises the usual series coils 57 and 58 and the potential coil 59 and. is interposed between the switch and the distributing lines H1 and H2. The

.switch-conductors 36 and 37 are connected,

either directly or indirectly, to the power lines P1 andP2. When the switch is closed and the fuse plug is in proper condition, current is admitted through the switch and meter to the distributing lines H1 and H2.

lVhen the switch is closed, the handle member 5l occupies the position shown in Figs. l,

2 and 5, and in order to swing the handle to this position whereby to close the switchit is necessary first to push the closure plate 40 inwardly'thereby covering the aperture 38.

When it is necessary to replace the fuse plug the handle member 51 'must first be swung to the position shown in Fig..3 thus opening the switch before the lclosure plate 40 can be withdrawn.

The device thus provided is of simple and compact construction, and contains but fewl operative parts,A and these parts are of a character such that they can be manufactured very cheaply and readily without the use of special machinery. At the same time the-device provides -effective means for preventing theft of current and safety to the user.

I claim: j

l. In a device of the character described the combination of a casing having,` a scalable cover provided ,with an aperture, a switch mounted on the wall of said casing opposite said cover having 4its terminals accessible when said cover is open, said switch comprising a switch` arm adapted'to oscillate about an axis in linel with the center of said aperture to open and `close saidv switch, said switch having a" non-conducting member preventing accessthrough' said aperture to lthe terminals of said switch when said cover is closed, a fuse mounted on said nonl conducting member and removable and replaceable through said aperture,'a closure for closing and opening said aperture, and means for locking said closure "in closed position whenever said switch is closed and releasing said closurey when said switch is open.

` 2. In a device .of the character described the combination of a casing having a scalable fcover provided with an aperture, a switch mounted yon the wall of said casing opposite said cover having 'itsterminals accessible when said cover is open, said switch comprising a switch arm adapted to oscillate about an axis in line with the center of said aperture to open and close said switch, said switch having a non-conducting member preventing access through said aperture to the terminals of said switch when said cover lis closed, -a fuse mounted on said non-conducting memextending arm engagin :said closure in closed position whenever said switch is closed and releasing said closure when said switch'is open, said fuse being a plug fuse having its axis 'in line with the axis of oscillation of said switch arm.

8. In a device ofthe character described the combination of a casinghaving a scalable cover provided withan aperture, a switch mounted on rthe wall of said casing opposite said cover having its terminals accessible when saidycover is open, said switch comprising a switch arm adapted to oscillate about an axis in linewith the center of said aperture to open and close said switch, said switch having a rotatable non-conducting switch arm carrying member prevent-ing access through said aperture to the terminals of said switch when said cover is closed, a fuse mounted on said non-conducting member and removable and replaceable through said aperture, a closure for closing and opening said aperture, and means for locking said closure in closed position whenever said switch is closed and releasing said closure when said switch is open, said cover having a rfc-entrant portion through 'which said non-conducting member protrudes.

4. A device of the class described compristherein, a member rotating in said opening, a frusto-conical insulating support attached at its larger end to said rotary member and having an axial bore in its smaller end, a fuse receptacle seated in said bore, oppo'sitely` directed relatively insulated switch blades car-v ried by the support, lixed switch members mounted upon the base cooperable with the respective switch blades, electrical conductors vconnected to the fixed switch members, and means for turning the support;

5. A device of the class described comprisY ing a box, a base plate secured to the inner surface of yone wall of the box, the central part ofthe plate beingspacedffrom said wall, the plate having a journal opening therethrough, a member rotating in' said opening, a lever armdisposed between the inner surface of said wall of the box and the rear side of the plate., said arm being secured at one end to one end of said rotating member and having an elongate opening at its other end, a support mounted upon the forward `end of switch element carried by the support, and a handle outside of the box having an inwardly g the elongate open- 1ng`1n the lever, arm for turning the' support.

6. A device'of the class described compris- ,ing a base plate having a journal opening therethrough` a. U-shaped bracket having parallel legs, said legs being-disposed within the opening 1n the base and constituting an axle Cal llU

for the bracket, a lever arm attached to the closed end of the bracket and extending substantially parallel to one face of the base, attaching ears projecting oppositely -from the tree ends ot the legs ot' the bracket and extending substantially parallel to the other face ot the base, a support attached to said ears, a fuse receptacle mounted on the support, switch blades carried by the support, relatively fixed switchelements cooperable With the respective blades, and means engag ing the lever arm to turn the bracket v7. A device of the class described comprising a box, a rotary support inside ot the box, a fuse-plug and switch element mounted upon the support, a lever arm carried bythe support,`a handle' member comprising a straight central part journalied in an opening in the wall of the box, the handle having portions substantially at right angles to said central part, onedot said portions being outside of.

t-he box, and a fixed bracket on the outside of the box having an elongate slot for. guiding the latter part of the handle, the other ot said handle portions being inside of the box and engaging the lever arm whereby oscillation of the handle turns the support.

8. A device of the class described comprising a normally Aclosed container, a fuse recepytacle Within the container, said receptacle being spaced inwardly from one Wallof the containerfthe container having a circular ap erture in said Wall coaxial with ther fuse receptacle, an annular guard mounted upon and projecting inwardly from said Wall, said guard being coaxial with the aperture and at its inner edge embracing the receptacle, a closure for the aperture, an oscillating circuit controlling switch having its axis in line with lthe center of said' apeiture, and means locking said closure ina closed position so long as the switch is positioned to-.complete the circuit tlie axis of said fuse receptacle being xed relatively to said openino.

'9. A device of the class described comprising a normally closed and locked container provided with openings for the admission of electrical conductors` terminals for such conductors disposed within the container, a fixed lbase within the container, a rotary support mounted on the base, said support having a circular portion and a peripheral shoulder, means torrotating the support, a fuse receptacle carried by the support in concentric relation to the axis ot rotation thereof, one walt of the container having an aperture coaxial with said axis, andan annular guard meinbei secured at one edge to said Wall"in coucentric relation to said aperture and axis and having its opposite edge closely embracing the circular portion of said support and overlying the peripheral shoulder of the latter, said support entering one end ot' said annular guard and having its axis ot rotationiixed relatively thereto.

l0. A device ofthe class described comprising a container, a removable covei therefor having an opening, a rotatable member in the container carrying a fuse receptacle and the movable members of a switch, the axis of rotation of said rotatable member being concentric with said opening, the fuse receptacle being positioned at the opening in the cover and closing said opening. when the cover is closed, a supplemental cover adapted when closed to preventaccess to the fuse and fuse receptacle, and a switch operating member accessible outside of the container and adapted to oscillate said rotatable member in said openingto open and close the switch, said switch operating member having a part cooperating with the supplemental cover to prevent tlie latter from being openedwlien the rotatable member is in switch closing position` the' axis of said rotatable member being fixed relatively to said aperture.

' ll. A device of the class described comprising a container, a removable cover theretor having an opening, a rotatable member in the container carrying a fuse receptacle and the movable member ofa switch, the axis of rotation of said rotatable member being concentric With said opening, the fuse receptacle being positioned at the opening in the cover and closing said opening when the cover is closed. a supplemental cover adapted when closed to prevent access to the fuse and fuse receptacle, and a switch operating member journalled in the wall of the container for oscillation on an axis at right angles to the axis of the rotatable member, accessible outside of the container and adapted to oscill'ate said rotatable member in-said opening to open and close the switch, said switch operating membei' having a part cooperating with the supplemental cover to prevent the latter from be'- ing opened when the rotatable member is in switch closing position, the axis of said rotatable member being tixed relatively to said aperture.

Signed by me at Cambridge, Mass., this Sth day of May, 1925.

,GRiiNviLLn n. PALMER. 

